I like your Sourceforge App, but find the two cases of No Daylight Time and Put Winter Time kind of repetitive. If you really want to offer a different choice, replace No Daylight Time with No Longitude Shift (i.e., with 12 Noon straight North). Since I have to use the Eq of Time anyway, I prefer to count from Local Solar Time. See example calculation using a miniature model. Coordinates are generic in ShadowsPro by F. Blateyron. Thanks!